To operate my models from time to time i have a small oval of track with roco R3 (52 cm diameter) curves. When i tried to run a passenger train the walthers horizon coach in the consist derailed everytime. The problem was recognized very fast: When the truck moves out in the curve, the truckframe hits the damper and spring assembly which is attached to the underbody of the car. The solution i found is very simple and needs just 10 minutes of time. With an x-acto nife, i cut away the damper and spring assembly from the underbody. You must work with much caution not o dammage the assembly. After i removed all the 4 assemblies i glued them on the truck frame leaving a small slit between the assembly and the car body shell. Now, the damper and spring assembly moves out with the trucks. The trucks can move a bit wider then before and can now operate also on this small Roco R3 radius.
The car nearly looks like before, just the damper and spring assemblies sits a bit more wider inside.